1. Field of the Invention
The invention relates to an inductor and, more particularly, to an inductor with at least two different reductions in inductance.
2. Description of the Prior Art
An inductor is a passive electrical component that can store energy in a magnetic field created by the electric current passing through it. An inductor's ability to store magnetic energy is measured by its inductance. Typically an inductor is a conducting wire shaped as a coil, the loops helping to create a strong magnetic field inside the coil due to Faraday's Law of Induction. Inductance is an effect resulting from the magnetic field that forms around a current-carrying conductor which tends to resist changes in the current. The number of loops, the size of each loop, and the material it is wrapped around all affect the inductance. For example, the magnetic flux linking these turns can be increased by coiling the conductor around a material with a high permeability such as ferrite magnet.
In electromagnetism, permeability is the degree of magnetization that a material obtains in response to an applied magnetic field. The permeability of a magnetic material is the ability of the material to increase the flux intensity or flux density within the material when electric current flows through a conductor wrapped around the magnetic materials providing the magnetization force. In general, when electric current flows through a conventional inductor, only one permeability can be obtained. Therefore, the usage of the conventional inductor is limited.
Furthermore, for those of ordinary skill in the art, an inductive coil is usually not suitable for current measurement due to the variation of resistance with temperature. Specifically, an inductive coil is generally made with copper coils. Since the copper has a relative high temperature coefficient of resistance (TCR), as the current passes through the copper coils, the coils experience a temperature rise. A higher temperature in turn causes a higher resistance in the coils with a positive TCR. The variation of the resistance in turn causes a change in the current conducted in the coils. For these reasons, in order to measure a direct current conducted in the coils, a separate resistor that is serially connected to the coils is often required.
Therefore, a need still exists in the art of design to provide a novel and improved inductor with at least two different reductions in inductance. In order simplify the implementation configuration with reduced cost; it is desirable to first eliminate the requirement of using a separate resistor for current measurement. It is desirable that the improved inductor configuration can be simplified to achieve lower production costs, high production yield while capable of providing inductor that more compact with lower profile such that the inductor can be conveniently integrated into miniaturized electronic devices. It is further desirable the new and improved inductor can improve the production yield with simplified configuration.